Current methods for the treatment of ectoparasites, e.g. lice, utilize insecticidal compositions which are available in both prescription and over-the-counter formulations. Such compositions generally include one or more of the active ingredients benzyl benzoate, pyrethrin, permithrin, and lindane. Dispensing formulations include lotions, creams, shampoos, cream rinses, and gels.
However, increasing numbers of ectoparasite infections, especially head lice, that are resistant to the above insecticides have been reported in the medical literature.
Alternative insecticidal treatments such as the use of malathion, ivermectin, and a combination of trimethoprim and sulfamethazole have been tried, but usually only with mixed results.
Another approach that has been reported and which is effective is the use of topical petrolatum-containing products, which suffocate the parasites when left on the head overnight. However, removal of the petrolatum from the head and hair has proven to be a difficult problem, often taking about ten days for complete removal.